Invalidity dossier
US 6005981
Quadtree-structured coding of color images and intra-coded images
Current assignee: National Semiconductor Corp
Added 9/24/2026, 1:18:11 AM
Active provider: DeepSeek · deepseek-flash
Patent summary
Title, assignee, inventors, filing/issue dates, abstract, and a plain-language overview of the claims.
Patent Overview — US 6005981 A
Title: Quadtree-structured coding of color images and intra-coded images
Patent number: US 6005981 A
Application number: US08/631,652
Inventors: Hak-Leong Ng; Xiaonong Ran
Original/current assignee: National Semiconductor Corp
Prior art date / filing date: 1996-04-11
Publication (grant) date: 1999-12-21
Legal status (as listed): Expired – Lifetime; anticipated expiration 2016-04-11
Classifications include: G06T9/40 (tree coding, e.g. quadtree); H04N19/96 (quad-tree coding)
Purpose. The invention relates to systems and methods for encoding, compressing, and transmitting or storing video or still images. The stated goal is high compression from a relatively low-complexity coding process; the text notes that an ideal encoder has low computational complexity, high compression, and high post-encoding image quality, and that these are difficult to achieve together.
Plain-language scope (per the supplied text). The encoder uses quadtree-structured coding. Where multiple two-dimensional arrays of pixel color components represent a frame, the quadtree structure for a first color-component array is restricted to being a sub-tree of the quadtree structure for a second array, so the sub-tree is transmitted or stored once while representing information for two or three arrays, reducing code lengths. Blocks may be coded by multiple methods — for example both inter-coded and intra-coded — with the shorter resulting code placed in the compressed bit stream. To limit complexity, a first code is compared to a threshold length and the second code is computed only if the first exceeds that threshold. In a software encoder, complexity may be preset or adjusted at run time according to processor or channel utilization by changing the threshold length.
Source: https://patents.google.com/patent/US6005981/en
What the excerpt does not establish. The supplied text is marked as excerpted, and its rendering is incomplete (e.g., a reference to U.S. Pat. No. 5,446,806 is truncated). It does not provide the full claim set, the complete detailed description or figures, the full prior-art discussion, or any prosecution history. It also does not establish validity, ownership transfers, or litigation. The legal-status and priority-date entries are expressly described in the source as assumptions, not legal conclusions.
Generated 10/1/2026, 9:31:30 PM
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Assignment history
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Prior art
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